US patent application US 2014/0265037 discloses a device for heating a feedstock of meltable or flowable material. The device comprises a heating body of electrically conductive material with one or more inlet orifices where the feedstock is introduced and one or more outlet orifices for said feedstock to exit after being heated. One or more passages or mixing chambers are provided that connect the inlet orifices and outlet orifices, comprising a nozzle. The nozzle body is sandwiched between two ends of, or inserted through a hole or gap in, a continuous or segmented core of material having high magnetic permeability but low electrical conductivity, forming a complete magnetic loop. One or more coils of electrically conductive wire pass through the center of the loop and around the outside of the loop. The device further comprises one or more sources of high frequency alternating current connected to the one or more coils. Eddy currents are induced by the magnetic field in the electrically conductive nozzle, which provide heating thereof. In an embodiment the continuous or segmented core is a torus shaped core.
US patent application US 2015/0140153 discloses an inductively heated extruder heater or adhesive dispenser using an electrically conductive nozzle with an inlet orifice and an outlet orifice connected by a passage. The nozzle is inserted into a gap or hole through a core formed in the shape of a loop or toroid, composed of soft magnetic material of high magnetic permeability and low electrical conductivity. A high-frequency alternating current is supplied to the coil, inducing a magnetic field in the magnetic core. The magnetic field, when passing through the electrically conductive nozzle, induces eddy currents that heat the nozzle to melt the material entering the inlet.
European patent application EP 2 842 724 discloses an induction heating system and a method for controlling a process temperature for induction heating of a workpiece. The induction heating system comprises an inductor configured to generate an alternating magnetic field in response to an alternating current supplied thereto. A magnetic load is provided comprising a magnetic material having a Curie temperature and being configured to generate heat in response to the alternating magnetic field being applied.
US patent application US 2003/0121908 discloses an apparatus for heating a flowable material. The apparatus comprises a core having a passageway formed therein for the communication of the flowable material, and an electric element coiled in multiple turns against the core in a helical pattern. The electric element, in use, heats the core both resistively and inductively.